 2.8  Sally-descent (see [1]}): Let \((A,\mathfrak {m})\)  be a Cohen-Macaulay local ring of dimension \(d\)  and \(M\)  be Cohen-Macaulay module of dimension \(r\) . Let \(x_1,\ldots ,x_c\)  be a \(M\) -superficial sequence with \(c\le r\) . Set \(N=M/(x_1,\ldots ,x_c)M\)  then
